The Falls of the Big Sioux were carved in the hard Sioux Quartzite sedementary rock by the Big Sioux River near the end of the Wisconsin Ice age, 14,000 years ago. The sand that eventually became this quartzite was deposited around 1.6 billion years ago by a series of southeastward draining plexus of braided streams flowing into a shallow inland sea. The rock is pinkish, interlaced with deposits of claystone (Pipestone), and shale, most of which are shades of light to very dark pink. The red color comes from Iron Oxide. The Pipestone was quarried at three or more locations by pale-Indian to modern Indian tribes. Two of the more prominent locations being Pipstone National Monument in S.D. Minnesota, and the ancient quarry at Palisades State Park near Garretson, S.D. Silver was also mined for a short time at Palisades, while Uranium test holes were dug near Brandon, S.D. Silver deposits were found in these drillings. Paleo-placer gold deposits are a possibility in Quartize areas.

The strong, hard Sioux Quartzite was quarried in numerous locations. Many of the historic buildings in the area are made from this stone. Masons were brought from Scandanavia to do the cutting and shaping. The Sweetman quarries near Sioux Falls are still a major source of Sioux Quartzite for construction. Sioux Quartzite has a hardness of 7 on the Mohs scale. The shale and claystone layers range from inches to 30 feet thick, while the quartzite itself can be over 500 feet thick. Ripple marks indicate a shallow water scenario. In early Plaeozoic times, the quartzite was a steep mesa hundreds of feet above the surrounding land. During later Paleozoic times, the western edge of the quartzite sank as far as 2,500 feet below the surface. It was covered by deposits of the great Cretaceous Sea around 70 million years ago, while the eastern edge stayed on the surface awaiting the scouring it received by the ice sheets. These great ice bodies left striations on the quartzite showing direction of glacial flow. The color of this text is roughly the color of Sioux Quartzite. For more information on the history of the Falls of the Big Sioux River, go to: http://www.siouxfalls.org/information/history.asp